纳米SiO_2粒子填充聚苯乙烯悬浮体系的动态流变行为

Dynamic Rheology of Nanoparticles Filled Polystyrene Suspensions

采用经典的溶胶-凝胶(Sol-gel)法合成直径50 nm的二氧化硅(SiO2)粒子,通过"两相"模型对不同粒子体积分数(φ)的二氧化硅/聚苯乙烯(SiO2/PS)悬浮体系动态粘弹行为进行拟合,讨论温度与φ对频率依赖性动态流变的影响。研究发现,应变放大因子Af和"粒子相"特征模量Rf″(φ)均随φ增加而增大;Af几乎无温度依赖性,Rf″(φ)随温度升高而降低。该现象归因于温度升高加速了由扩散控制的SiO2团聚过程,导致纳米粒子比表面积减小,抑制了粒子网络的形成。研究表明,两相模型可很好地应用于SiO2/PS悬浮体系的动态流变行为。

Influences of temperature(T) and particle weight fraction(φ) on frequency-dependent loss modulus of silicon dioxide(SiO2) nanoparticle synthesized by the classical sol-gel method dispersed polystyrene(SiO2/PS) suspensions were studied in the framework of a two-phase model. It was revealed that the amplification factor Af(φ) and characteristic loss modulus R′′f(φ) of the 'filler phase'increased with weight φ. While Af(φ) was hardly dependent on temperature, R′′f(φ) decreased gradually as temperature increased, which could be attributed in part to the accelerated diffusion-controlled SiO2aggregation and the reduced specific surface areas of the particle phase with PS chains absorbed on the particle surface. The results showed that the two-phase model could be successfully applied to describe the dynamic rheology of SiO2/PS suspensions.